Art of cross-rolling tubular bodies or blanks in a heated state.



PATENTED' JUNE 13, 1905,

J. H. NIGHOLSO ART OF (moss ROLLING TUBULAR BODIES 0 APPLICATION FILED R BLANKS IN A HEATED STATE.

PATENTED JUNE 13, 1905.

J. H. NICHOLSON. ART OF GROSS ROLLING TUBULAR BODIES 0R BLANKS IN A HEATED STATE.

APPLICATION FILED APR. 1, 1904.

3 SHEETS-SHEET 2.

792,231- PATENTED JUNE 13, 1905.

SON.

0E BLANKS m A HEATED STATE. PR.1,1904.

NIGHOL BODIES N FILED A 3 SHEETS-SHEET 3.

Q J. H. ART OF CROSS ROLLING TUBULAR APPLICATIO UNITED STATES Patented June 13, 1905.

PATENT OFFICE.

JOHN H. NICHOLSON, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO NATIONAL TUBE COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEWV JERSEY.

ART OF CROSS-ROLLING TUBULAR BODIES 0R BLANKS IN A HEATED STATE.

SPECIFICATION forming part of Letters Patent No. 792,231, dated June 13, 1905. Application filed April 1, 1904. Serial No. 201,077.

To all whom it may concern.-

Be it known that I, JOHN H. NICHOLSON, third vice-president of the Shelby Steel Tube Company, a citizen of the United States, and a resident of Pittsburg, Pennsylvania, (postoffice address, care of National Tube Coinpany, Frick Building, Pittsburg, Pennsylvania,) have invented certain new and useful Improvements in the Art of Cross-Rolling Tubular Bodies or Blanks in a Heated State, of which the following is a description, illustrated and exemplified by drawings.

The cross-rolling process as invented by the Mannesmanns and improved by Ralph Charles Stiefel and others, while satisfactory under certain conditions, has given considerable trouble where it is desired to make small tubes with thin smooth walls in a single pass without undue strains upon the metal. In these processes the piercing-point is a conical-shaped mandrel which has an uninterrupted continuous conical surface, which acts as an anvil over which the billet is advanced, the revolving rolls rotating the billet, impinging the metal, and reducing the thickness of the wall of the forming tube. This opera tion produces a hollow blank or tube, the thickness of the wall being dependent upon the size of the piercing-mandrel and the opening or pass between the rolls, and it is a general law in piercing with these types of machines that the thinner the wall the larger the diameter of the tube and the more severe the stress of strains put upon the physical conditions of the metal.

It is the prime object of the present improvement to divide or split up the piercing operation into a number of different steps or suboperations (but all being performed simultaneously on the same machine) for the purpose of improving and bettering the conditions under which the walls are decreased in thickness and whereby the lineal length of the tube can be increased and at the same time hold any desired outside diameter independent of the thickness of the wall.

Tubes can be produced by this process of such smooth finish and thinness that they can shown in section.

be taken direct to the cold-draw bench for fiu-= ishing without any subsequent rolling operation, as is customarily used, and can be colddrawn to a finish with as few passes as is now required for the swaged or rolled blank. NO difficulty is encountered in securinga pierced blank sufficiently long to make any of the standard lengths required for pipe or boilertubes.

These and certain other aims and advantages will readily be apparent to those skilled in the art; and the improvement consists in the process and certain of the subprocesses or individual steps thereof as are set forth and claimed herein.

The invention will be readily understood from an immediate description of the accompanying drawings, wherein- Figure l is a diagrammatic illustration, partly in longitudinal section, through a pass, showing the rolls and plugs or mandrels in full and the metal in section. Fig. 1 is a cross-section on the plane 1 of Fig.1. Fig.2isasimilar view of a modification, part of one roll being Fig. 3 is a view similar to Fig. 2, showing another form of the invention. Fig. 4 shows a special application of the invention to reducing the wall thickness without enlarging the diameter of the tube.

In Fig. 1, B, C, and D are three plugs or mandrels independently rotatable and coaxially mounted one in front of the other upon a mandrel-bar F. G and Ham rolls, preferably equal rolls, having aplurality of conical or conoidal surfaces that cooperate with the plugs B, C, and D. J and K are guides which, as shown, snugly surround and guide the blank or tube Lat substantially all points except where the rolls G and H act upon it. It will be noticed in Fig. 1 that the tubular body L, as well understood, will be slightly elliptical in form, while under the action of the rolls G and H of course the guides J K must conform and allow for this ellipticity and longitudinally should be profiled in the same way that the rolls are profiled to form the pass. The rolls, as well understood, are preferably skewed to produce a feeding cf- .plug C.

pass.

fect, though some parts of the process and some advantages may be derived without skewing the rolls, the metal being forced through by a ram. The rolls G and H have rolling-surfaces 10, 11, 12, 13, and 1 1. Surfaces 10 form a converging portion of the pass, which in cooperation with the diverging portions '11 and the piercing or expanding mandrel B first cause the rolling, compressing, and feeding of the metal onto the point of the plug B and then the expansion and reduction of the wall thickness upon the larger base portions of the plug B.

In Fig. 1 provision is found for thinning the wall of the tube without at the same time enlarging it too much. Thusthe rolling-surfaces 12 compress and reduce the tube exteriorly without anyinterior support fromthe tube and they force thetube onto'the plug C at a somewhat smaller diameter than the largestpartofplugB. Therolling-surfaces13 diverge, and consequently compress, expand, and reduce the thickness of the tube uponthe Plug C therefore repeats an effect similar to that of-the base portion of plug B. Finally, plug D is a cylindrical smoothingplug which cooperates with the rolling-surfaces 1 1 of the rolls, which form between them a parallel and not a diverging portion of the The interval between the plug D and the rolling surfaces 14 should converge slightly, too slightly to be noticed in the drawings, so as to merely smooth out the irregularities on the interior and exterior of the tubular wall without materially expanding or materially thinning the wall. Plugs B, U, and D cooperate with progressively increasing diameters of the exterior rolling-surfaces, the mean diameter of the surfaces 13 being greater than that of surfaces 11 and the mean diameter of surfaces 14 being greater than that of surfaces 13. The exterior rolling-surfaces therefore have a progressively-increasing peripheral speed from front to rear of the pass, and

the plugs B, C, andD in order to have proper speed relations with the external bodies must be free to rotate relatively to each other. This is accomplished by mounting the plug D so that it is free to turn upon the projecting end of the mandrel-barF. (Seen in dotted lines within it.) The plug C is likewise mounted so as to turn'freely upon the end of the mandrel-bar, and one or more washers 16 are preferably interposed between C and D to take the end thrust. Plug B has a rearward-extending center or trunnion 17, which fits a recess in the plug 0 and permits the point or plug B to turn relatively to the plug 0. A washer 18 is interposed between them. By increasing or decreasing the thickness of washers 16 the plug C may be adjusted longitudinally, and thereby the space between the plug C and the rolling-surfaces 13 may be adjusted with great nicety. Similarly the washers 18 may be of different thicknesses to nicely adjust the position of plug B longitudinally; but in addition to permitting adjustment these washers are of great importance as compeneating for the wear, which is very much greater upon the plugs B and C than upon the plug D. Owing to the increased peripheral speed of the larger diameters of the rolls G and H and a consequent increased speed effect due to the skew of the roll, there is a tendency for theheated metal that is being rolled to travel more rapidly between the plug D and the surfaces 1 1 than between the plug B and the surfaces 11 and 10. This is found in practice to produce an elongated or tensile effect upon the metal in the pass, and it is also found to go through the pass with less expenditure of mechanical energy than would otherwise be the case. This is of course largely due to the independentrotation ofthe successive plugs B, C, and D, which contributesto this advantageous effectand not only reduces the powerrequired, but also greatlylessens stresses and strains to which the metal is subjected.

It-is possible by'the combination of the various steps of-this process to'roll a tube with a thin smooth wall without any undue strains in the metal and to accomplish'this at a single pass, so that the tube is ready for finishing on a cold-draw bench Without the subsequent usual rollingoperation. From a given size of billet or blank it seems possible to make thinner walls with smaller sizes of tube than hasheretofore been thought possible of attainment by the known processes.

In Fig. 2 the rolling-bodies are in the form of disks M and N. The plugs B, C, and D are substantially the same as in Fig. 1. Several adjustment-washers 16 and 18 are shown, and the exterior rolling-surfaces of the rolls or'disks M and N are also shown adjustable by means of the removable rings 20 21, se-

cured byadjustable bolts 22 and backed by washers 23 and 2 1. This construction is valuable not only as permitting-adjustment, if necessary, of the width of the pass, but more particularly as permitting the compensation for the wearing away of the rolling-surface. As the surfaces wear away additional annular washers 23 and 24 may be inserted or thicker ones substituted for those already in place.

Fig. 3 differs inprinciple from Figs. 1 and 2'only in theomission of the intermediate plug C. This figure therefore provides only for the initial action upon the plug B and the smoothing and finishing action upon the plug D.

Fig. 4, on the other hand, shows three sue cessive plugs C forthinningthe wall of the tube, and-the rolls P Qhave successive sets of cooperating converging and'diverging surfaces 112 113, 212 213, 312 313. The plugD cooperates with the-rolling-surfaces 1 1, thatcorrespond with surfaces 14 in the other fig mast hres. In this figure it will be seen that the metal is compressed against the expanding plug-surfaces and reduced in thickness while being enlarged in diameter, and then it is again compressed, so as to reduce the external diameter, and again rolled thinner upon an ex panding surface, and so on to the final finishing-plug D.

The apparatus illustrated and described forms the subject-matter of a separate patent application, Serial No. 201,07 8, filed April 1, 1904:, and the carrying out of the present process is not, so far as I am aware, limited to the particular form of apparatus illustrated.

l/Vhat I claim is An improvement in the process of crossrolling tubular bodies or blanks in a heated state, which improvement consists in rolling and compressing interiorly and exteriorly the heated body at one portion of the pass and subsequently compressing the heated body exteriorly only and thereby reducing its external diameter, and subsequently rolling and compressing it between exterior and interior rollingsurfaces, for substantially the purposes set forth.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

JOHN H. NICHOLSON.

H. W. PHELPS. 

